How get drawing area in callback for quadview?
Thanks to CoDEmanX, I have the solution:

 if not context.space_data.region_quadviews:
        rv3d = bpy.context.space_data.region_3d
    else:
        # verify area 
        if context.area.type != 'VIEW_3D' or context.space_data.type != 'VIEW_3D':
            return
        i = -1
        for region in context.area.regions:
            if region.type == 'WINDOW':
                i += 1
                if context.region.id == region.id:
                    break
        else:
            return

        rv3d = context.space_data.region_quadviews[i]